In the prior art, various methods and devices have been proposed for assaying various substances. U.S. Pat. No. 4,770,853 to Bernstein discloses a device for self-contained solid-phase immunodiffusion assay comprising a sample collector, a tube with compartmentalized reagents and a ligand receptor capture membrane filter area. The sample collector is pushed through seals in the device and is mixed with reagent, and then pushed into a ligand receptor reaction area. A tip of the sample collector contacts diffusible membranes and transfers the reactants to a capture membrane for visualization of a ligand receptor reaction by a viewer.
U.S. Pat. No. 4,818,677 to Hay-Kaufman et al. discloses methods and a kit for performing immunoassays. The kit includes a reaction cell having a micro-porous membrane and an absorbent capable of drawing a liquid sample through the membrane. Analyte in the sample is immobilized, typically by immunoadsorption, and the immobilized analyte may then be visualized using conventional signal producing systems, such as color, fluorescence and luminescent systems.
U.S. Pat. No. 5,043,260 to Jauregui discloses a perfusion device to grow and maintain hepatocytes including a chamber having a perfusion inlet and a perfusion outlet. A semipermeable membrane in the chamber defines separate perfusion and hepatocyte compartments, the hepatocytes therein being attached via oligosaccharide-lectin recognition linkage to a biopolymer support in the hepatocyte compartment.
The prior art also teaches immunochemically-based methodologies for the detection of small or large molecular weight substances. Exemplary of these methodologies include radioimmunoassay, enzyme-linked immunosorbent assay, enzyme multiplied immunoassay, enzyme immunoassay, fluorescent immunoassay, nephelometric inhibition immunoassay, hemagglutination inhibition, microbiologic assay, free radical assay technique--also called spin immunoassay, liposome immunoassay and potentiometric immunoassay.
U.S. Pat. Nos. 5,002,871 and 5,037,741 to Iacobucci disclose a membrane method for the enzymatic synthesis of peptides. The method employs a membrane permeable to uncharged peptides but impermeable to charged molecules. The enzymatic method provides a process for the safe, economical and efficient synthesis and purification of peptides and derivatives thereof, and the efficient use of enzymes and the means to affect the synthesis on a continuous basis.
Disadvantages of currently used immunoassays include difficulty when using under field conditions, expensive, difficult to perform without training, time consuming and the requirement of multiple reagents, many of which can undergo degradation and, thus, interfere with test results. In view of the deficiencies in prior art detection methodologies, a need has developed to provide a rapid, portable, easy to use, inexpensive and versatile assaying apparatus and method.
In response to this need, the present invention provides an assaying apparatus and method which overcomes the deficiencies in the prior art. The inventive assaying apparatus and method provides results within a few minutes, requires a small number and small volume of reagents, utilizes simple chemical reactions to perform given assays, provides long shelf life reagents and provides easily interpreted assay results.